1. Field of the Invention
The present invention relates to containers and, more particularly, to plastic fluid container base cups having reduced heat gain and good recycleability.
2. Background of the Invention
Of course, containers such as plastic bottles, are popular for beverages, such as soft drinks. After such a container is removed from the refrigerator, cooler, etc., the beverage undesirably begins to warm.
More particularly, heat is conducted from the surroundings, through the beverage container, and to the beverage contained therein by three primary modes of heat transfer. First, any difference in temperature between a container""s surroundings (such as the air surrounding the container or the surface the container is placed on) and heat will be conducted through the container wall and enter the beverage by convection. Second, heat can also enter the container wall as a result of condensation of moisture from the air on the surface of the container. For each drop of water condensing on the surface, there is energy in the form of latent heat of condensation transferred to the container wall. Third, and the greatest source of heat to the container wall, is direct radiation from the sun and ground. For example, with a plastic bottle, thermal radiation easily penetrates the plastic bottle wall. As the radiation penetrates, it heats the plastic from within, as well as on its outer surface, further hastening the heating of the container contents.
Accordingly, it is a purpose of the present invention to provide a container capable of retaining the cold temperature of its contents for a longer period of time than the prior art.
It is another purpose of the present invention to provide a container, which retards heat gain caused by radiation, conduction, convection or condensation.
It is another purpose of the present invention to provide a container having an external reflective layer, which is capable of reducing heat gain caused by radiation.
It is another purpose of the present invention to provide a container that uses a foam layer to reduce heat gain caused primarily by convection, conduction, or condensation.
It is another purpose of the present invention to provide a passive base cup for receiving a bottom of a plastic beverage container for further reducing heat gain through radiation, conduction, and convection heating of the bottom and beverage contents.
It is still another purpose of the present invention to provide a beverage container active base cup which contains a freezable phase change fluid for receiving a bottom of the beverage container and further reducing heat gain through radiation, conduction and convection heating of the bottom and beverage contents.
It is also a purpose of the present invention to provide a method for forming a reduced heat gain container.
To achieve the foregoing and other purposes of the present invention, a container body bottom is received by a base cup. The container body can be a conventional plastic beverage container, or a plastic container having a layer that reflects radiation formed thereon, and optionally a foam layer with the reflective layer.
The base cup may be made of a polymer and have an outer reflective layer to further increase the thermal resistance of the container body. A foam layer can be placed over or under the reflective layer to further improve heat gain suppression. Alternatively, the base cup can be made of foam with a reflective layer thereon. A space inside the base cup may contain air, if the cup is to be a xe2x80x9cpassivexe2x80x9d insulator for the bottom of the container body, or a fluid that can be frozen, to provide an xe2x80x9cactivexe2x80x9d base cup.
The container body and base cup can still be efficiently recycled by using separation techniques based on density of the various materials. The materials of the reflective layer are selected to have a density less than 1 g/cc so that the reflective layer can be separated from the container body having a density greater than 1 g/cc. Alternatively, if the reflective material density is selected to be greater than 1 g/cc, then the addition of a foam layer can reduce the bulk density of the structure such that the combination has a density less than 1 g/cc. In addition, the passive base cup materials can be selected such that the density is less than 1 g/cc, or combined with foam to create a structure such that the combination has a density less than 1 g/cc. The inverse is true when the container body density is less than 1 g/cc.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.